At the present time, waste disposal from an Inductively Coupled Plasma System for atomic spectroscopy is conducted through a single drain tube assembly connected to a plasma torch unit of the system. As is shown in FIG. 1, this assembly includes a sample introduction system which consists of a neublizer, spray chamber, an outlet to a flame or plasma and a waste outlet. The majority of the sample is discharged from the system as waste through a single drain line. As can be seen from FIG. 2, this drain line consists of flow tubing and a trap T. The trap T is provided to maintain a positive back pressure in the system as well as to provide protection against the build-up of gases within the drain vessel.
Sample preparation for atomic spectroscopy frequently requires the handling of corrosive organic or aqueous solutions. This may require the dilution of liquid samples or the more hazardous procedure of dissolving a solid sample in a solution. These procedures are set forth in Environmental Protection Agency (EPA) guidelines for safe laboratory practice.
During the sampling process, in order to maintain optimum performance of the system, the drain must be kept clean and free flowing. In order to achieve this the drain must be cleaned frequently thereby interrupting the sampling procedure. Further, the drain assembly must be routinely inspected, and any deteriorating portions must be replaced resulting in additional downtime of the sampling system.
It is also often desired to test samples of different types which require various solvents. These various solvents are often incompatible with one another and if mixed could result in a toxic hazardous solution. In order to eliminate any likelihood that those substances will in fact mix, the system is disassembled and cleaned after each use. Again, this procedure is necessary to ensure the safety of the operator, and results in a significant downtime in the operation of the sampling system.
In an effort to minimize the downtime of the analysis system, U.S. Pat. No. 4,722,830 to Urie et al., proposes an automated multiple stream system which provides a plurality of process sample streams whose delivery are controlled by a multiport valve. The system includes a pair of processing systems each being capable of analyzing a variety of samples on command with each having a single waste stream. However, this system is only concerned with the isolation of simultaneous process streams and has not considered the isolation of multiple sequential waste streams.
Clearly, there is a pressing need for a system which is capable of isolating multiple waste streams so as to minimize downtime due to a change in sample selection or maintenance while maintaining a safe environment around the system.